Blueberry and Chocolate Ribbon Torte

Prepare the shortbread base: Rub the cold, cubed butter into the flour until the mixture resembles fine breadcrumbs. Add the sugar and one egg, then quickly knead into a smooth dough, being careful not to overwork it. Wrap in cling film and chill in the fridge for 30 minutes.

Bake the base: Preheat your oven to 200°C (180°C fan/gas 6). Line a 26cm springform tin with baking parchment. Roll out the chilled dough to fit the pan, place it in the bottom, and prick it all over with a fork. Bake for 15-20 minutes until lightly golden. Allow it to cool completely in the tin.

Make the chocolate sponge: Maintain the oven temperature. Line a large, rimmed baking sheet with parchment. Separate 5 eggs into two bowls. Beat the yolks with 5 tbsp cold water and icing sugar until pale and fluffy. In the other bowl, whisk the egg whites to stiff peaks. Sift the flour and cocoa powder into the yolk mixture, then fold in a large spoonful of egg white to loosen. Gently fold in the remaining whites, preserving as much air as possible.

Bake and roll the sponge: Spread the batter evenly over the prepared baking sheet and bake for 10-12 minutes until spongy. While baking, dust a clean tea towel with cocoa powder. Once cooked, let the cake cool for 5 minutes, then invert it onto the towel. Roll the cake up tightly from the long side with the towel inside and leave to cool completely.